Estimation of relative permeability curves in porous media induced by electroosmotic flow through pore-scale two-phase flow simulations

Abstract

Given the limited research on two-phase electroosmotic flow within porous media, this paper conducts numerical simulations to investigate the pore-scale two-phase flow behavior and the relative permeability characteristics induced by electroosmotic flow. A two-phase slip velocity approximation model is employed to simulate water/oil two-phase electroosmotic flow in porous structures. The results indicate that, although the dragging capacity of the water phase increases with water saturation, the influence of capillary force and weak viscous coupling between small oil clusters and the water phase results in a non-monotonic trend in the relative permeability of the oil phase. Due to changes in the flow mechanism, the relative permeability of the water phase increases slowly before a certain level of water saturation. However, once the water saturation exceeds this threshold, the relative permeability of the water phase increases rapidly with further increases in water saturation. The increased flow resistance for the oil phase and the diminished electro-osmotic driving force for the water phase are the two primary factors responsible for the lowest oil-phase relative permeability observed in oil-wet porous media. The relative permeability curves for both the oil and water phases increase with the electric field strength under all three wettability conditions. Moreover, high electric field strength will reduce irreducible water saturation under water-wet conditions, but this phenomenon is not as pronounced under intermediate-wet and oil-wet conditions.